Underwriters Laboratories standard 294 (UL 294) entitled “Standard for Access Control System Units Equipment” requires each piece of equipment used for access control to pass a transient voltage test (TVT). Specifically, UL 294 requires an access controller to continue to operate while a 2400V transient voltage is present on any communications cable entering or leaving a room. A 2400V transient voltage far exceeds the limits of an Ethernet communications port. As a result, the TVT requirement of UL 294 restricts devices such as credential readers, door locks, request-to-exit devices, etc. from migrating to TCP/IP without transient voltage protection.
The 2400 TVT applies a 60 ms, 2400V spike between every combination of wires in a cable connecting to an access controller. Due to the proximity of the pins in an Ethernet jack, the 2400V TVT destroys the jack, leaving the access controller inoperable. In order to pass the TVT, an access controller must be able to operate normally during and after the 2400V TVT has been applied. Therefore, there is a need to create a device that has the ability to dissipate a transient while allowing an access controller to operate normally.